The jumpers are there to set the circuit up for voltage or current input and balanced / unbalanced mode.

There is a new version of the ZAP filter with simplified schematic... Have a look at the big CD upgrading PDF brochure, you'll find a schematic in there.

I did a PCB for this circuit... But until now I wasn't able to identify the transistors they use... Picture quality is not good enough, no info in the schematic. I'm using BC550 / BC560 for a first "proof of concept" prototype.

Originally posted by AMT-freak The jumpers are there to set the circuit up for voltage or current input and balanced / unbalanced mode.

There is a new version of the ZAP filter with simplified schematic... Have a look at the big CD upgrading PDF brochure, you'll find a schematic in there.

I did a PCB for this circuit... But until now I wasn't able to identify the transistors they use... Picture quality is not good enough, no info in the schematic. I'm using BC550 / BC560 for a first "proof of concept" prototype.

The brochure is too big for most mailboxes, you can download it from the link below. See page 17. Text is danish, but the schematic speaks for itself. Missing: the shunt regulators and (optional) DC servos. Those are pretty much the same as in the first ZAP filter version and can be used unmodified. I simulated it that way and it seemed to work.